Environmental sensing systems are required to provide information about environmental conditions, often across wide areas of terrain. For example, it may be desirable to monitor the temperature and humidity at various points across a commercial timberland as a means of detecting incipient or actual forest fires. It might be desirable to monitor air and ground humidity at various points in a farmland environment, to guide the proper application of irrigation water. It could even be desirable to monitor snow temperature and UV light received at various points in a snow field.
Various difficulties attend such monitoring schemes. It may be difficult to provide reliable electrical power in remote areas to power such monitors. It may be difficult to manage the large amount of data produced by a large number of monitors spread across a wide area. It may be difficult to assure reliable transmission of data, especially if environmental, or other, events, damage part of the system. Lastly, such monitoring may need to be dynamic, in that different measurement parameters may be desired at different times and under different conditions. These requirements may to some extent be mutually exclusive, for example, systems with highly reliable transmission may use excessive amounts of power.